Prions are infections agents made up of protein only. They cause a number of diseases in both humans and animals. The mode of infection involves a protein structural change from alpha helical to beta sheet form. We have refined the solution structure of the alpha helical form of a recombinant fragment of syrian hamster PrP gene product. This prion protein is known to exist in at least two different conformations. One solution form that is predominantly alpha helical (PrPc) and another, aggregated beta-sheet form (PrP Scrapie). The structural dimorphism in itself is interesting since it demonstrates that amino acid sequences can encode more than one structure, but more importantly, the sequence has significance in human pathology because it is involved in prion diseases. This project is significant for both drug design, and, on a more fundamental level, our ability to understand protein folding. Now that we have completed this structure we are beginning to examine another protein with similar properties, protein tau. This protein also undergoes a conformational change that is involved with Alzheimer's disease.